The suspension bridge
A racecar’s suspension is defined as a system of components mechanically connecting the road wheels to the chassis of a vehicle while allowing relative movement between them.
The suspension’s job is to communicate and manage all the forces generated at the tyre-track interface (the contact patch) into the chassis of the vehicle. Undulations in the track surface, lateral accelerations experienced in cornering, longitudinal accelerations due to braking and throttle, as well as steering inputs, all pass through the racecar’s suspension components. In reverse, the suspension system also defines how forces are transferred from the chassis into the contact patch through aerodynamic loading and weight transfer.
Load and balance
The manner in which the suspension system is designed and then set up is imperative in influencing not only the peak cornering loads of the racecar, but also cornering balance. It is therefore an area of substantial investment and R&D and sits alongside powertrain and aerodynamics as an extremely pivotal consideration for a racecar’s performance.
A conventional suspension system consists of wheels and tyres, structural components such as control arms, spring-damper systems and, more recently, further specialised and unique solutions in hydraulic systems –and a neat piece of technology known as an inerter.
The racecar suspension system’s prime task is to ensure that the tyre is operating in conditions that maximise forces generated at the contact patch. Being the sole point of contact between the car and the track surface, the tyres are the determining factor in the magnitude of all longitudinal and lateral forces generated during operation; the technology involved with racing tyres is therefore very important. While not directly part of the suspension system they are so inextricably linked that they really must be considered as an extension of it. The tyres also contribute to the frequency response of the unsprung and sprung mass – more on that in due course.
Modern race tyres are a mix of natural and synthetic polymers with an array of further compounds, such as carbon black, silica and sulphur, added to improve their various mechanical properties. To
